The present invention relates to an implantable device for receiving a heart valve or other implantable device.
Implantable heart valves are used to replace a diseased or otherwise damaged native heart valve in order to restore the heart to ordinary function. Typically, the valve is implanted in the annulus where the damaged valve was removed. Generally, there are two types of implantable heart valves: 1) "mechanical" valves; and 2) "tissue" valves. A mechanical valve includes pyrolitic carbon, metal or plastic surfaces which rotate or are otherwise displaced to regulate blood flow. A tissue valve includes all or part of a heart valve from a non-human, e.g., a porcine animal, a human valve transplant called a homograft, a valve constructed from animal tissue other than valve tissue, e.g. pericardial valves or transposition of a valve from one site to another site in the same person called an autograft to regulate blood flow. With both types of valves, a generally annular structure is frequently used to position and support the valve in the native annulus. An important goal of heart valve design is to minimize the obstruction of blood flowing through the native annulus.
In a common implantation procedure, the implantable heart valve is sewn into the native annulus, fixing the valve in place until native tissue growth around the valve provides a permanent attachment, see e.g., U.S. Pat. No. 3, 524,202. This implantation procedure is time consuming and requires good visual access to the native valve, as well as access for needles, needle holders, a valve seating device, and the surgeon's hands. This procedure requires cardiopulmonary bypass (CPB) and myocardial preservation measures to arrest the heart for an extended period. There measures have improved since early valve implantation procedures. Additionally, the current trend in surgery is toward less invasive surgical techniques.
One approach for reducing the implantation time is the use of "sutureless" heart valves, see e.g., U.S. Pat. Nos. 3,587,115, 3,464,065, 3,371,352, and 3,143,742. Such sutureless designs typically include pins positioned about the annular valve support structure. When the valve is positioned in the native annulus, a mechanism is used to drive the pins into the surrounding annulus tissue, thereby holding the valve in place until native tissue growth provides a permanent attachment. One limitation of these sutureless designs is that the pre-positioned pins and the driving mechanism increase the radial width of the valve support structure, thereby decreasing the size of the blood flow passage through the valve.
Another implantation approach incorporates a two-part valve assembly, see e.g., U.S. Pat. Nos. 4,892,541 and 4,680,031. The first part of the assembly is a sewing ring, which is positioned and manually sewn into the annulus as described above. The valve comprises the second part, and is removably coupled with the sewing ring. This approach provides for faster removal of a failed valve, but has the limitations described above for sewing the ring into the annulus.